CE-680A First Officer reported a DC generator failure. The flight returned to the departure airport.

Narrative

At FBO received our clearance to taxi to runway XXL. As we taxi to the runway via Taxiway 1 we had an Amber message DC GEN OFF L". We taxi back to the FBO; went through company QRH to reset the Left GEN. Procedure Completed with Voltage back to normal. We decided to taxi back to runway XXL. Before takeoff we received the same Amber message "DC GEN OFF L". Went through the same company QRH to reset and voltage went back to normal. We took off runway XXL reached an altitude of 1500 and received the same Amber message along with an abnormal sound coming from the engine. We decided to tell Approach we needed to come back to land on runway XXL no assistance needed. As we were setting up for the approach back in; we selected flaps 2 we then received at Flaps Failed Message. With that issue being related to flight controls and an [priority] item on our companies QRC we [requested priority handling]. As we went through the proper steps in the QRC we reset the flaps and that corrected the issue and then proceeded to have a normal landing. We then told Approach we no longer needed to [request priority handling]. We then flew straight in for the visual [Runway] XXL. We also had an APU MEL which left us with only one generator remaining."